A flash array is a storage system that includes a solid state disk and at least two controllers. The controller manages storage space of the solid state disk in a unit of segment. A segment is an area of contiguous logical addresses that is allocated by the controller. The segment is also a basic unit of system garbage collection. Each controller may write received data into a segment managed by the controller. Data received by the solid state disk from each controller is sequentially written into a block in the solid state disk in a time sequence of receiving the data. Therefore, data sent by all the controllers may be written into a same block within a time period. Therefore, data stored in each block may be corresponding to segments managed by different controllers.
After a flash array performs system garbage collection and releases some segments, a block in a solid state disk is not fully erased because the block still includes data in another segment on which system garbage collection is not performed. Therefore, when performing garbage collection in the solid state disk, the solid state disk still needs to write, into a blank block, the data in the block of the another segment on which system garbage collection is not performed. Consequently, a large quantity of times of write amplification occur in the solid state disk.